Email preview will appear here
Paste HTML and click Preview Email// preview email-safe html across simulated clients
Test and preview email-safe HTML with table-based layouts, inline styles, and multi-client rendering simulation. Free browser-based tool.
Email preview will appear here
Paste HTML and click Preview EmailPaste your email HTML into the editor, or click a snippet button to load a starter template.
Click "Preview Email" to render it. Switch between Gmail, Outlook, Apple Mail, and Mobile viewports.
Check the validation panel for email-safety issues, then use "Inline Styles" to auto-convert <style> blocks.
Email HTML is a special beast — modern CSS doesn't work reliably. You must use tables for layout, inline styles for most formatting, and avoid many CSS properties that email clients strip or ignore. This tool lets you preview and validate email HTML before sending.
Most email clients, especially Outlook, have extremely limited CSS support. Flexbox, Grid, and many modern CSS properties are simply ignored or broken. Table-based layouts remain the only truly cross-client safe approach for multi-column email design.
Many email clients strip <style> blocks from the <head>. The "Inline Styles" feature parses your <style> block and applies matching rules directly onto each element as inline style attributes — greatly improving compatibility with Gmail and other clients.
The previews simulate viewport widths and some rendering quirks of each client, but they are not pixel-perfect emulations. For production campaigns, always send test emails to real accounts. This tool is ideal for catching obvious issues early in development.
Avoid: Flexbox, CSS Grid, CSS Variables, calc(), most animations, external fonts (use web-safe fonts like Arial, Georgia), float (unreliable), and position: absolute/fixed. Stick to margin, padding, border, background-color, font-*, width, and color properties applied inline.
600px is the industry standard maximum width for email templates. This ensures the email renders well in most email clients across desktop and mobile, including when the Outlook preview pane is used. Mobile-specific styles should target widths below 480px.
No. This tool is entirely browser-based — all processing happens locally in your browser. No HTML is ever sent to any server. Your email templates remain completely private.
An HTML email template tester is a tool that lets you preview and validate the HTML code used in email campaigns before sending them to real recipients. Unlike web browsers, email clients render HTML using their own proprietary engines — often with drastically reduced CSS support. What looks perfect in Chrome may break completely in Outlook.
This tool renders your email HTML inside simulated viewport frames representing popular clients like Gmail, Outlook, Apple Mail, and mobile devices. It also performs static validation to catch common email HTML problems early in development.
💡 Looking for premium HTML templates and themes? MonsterONE offers unlimited downloads of professional email templates, UI kits, and web assets — worth checking out.
The web has largely standardized on modern CSS — but email hasn't. Email clients are notoriously fragmented in their rendering support. Outlook on Windows uses Microsoft Word's HTML rendering engine, not a browser. Gmail strips <style> blocks and class attributes in some contexts. Apple Mail is relatively modern but still has quirks.
This fragmentation means email developers must follow a set of strict conventions:
This tester provides four simulation modes, each representing a different rendering context:
The built-in validator scans your HTML for common email compatibility issues and assigns a score. It checks for:
Writing all styles inline from the start is tedious. Many developers prefer to write email CSS in a normal <style> block for readability, then convert to inline before sending. The "Inline Styles" button in this tool does exactly that — it parses your <style> rules, matches them against elements in the HTML using basic selector matching, and merges the declarations directly onto each matched element's style attribute.
This is a simplified implementation that handles class, element, and ID selectors. For complex pseudo-class or descendant selectors, a dedicated CSS inliner library (like juice for Node.js or Emogrifier for PHP) is recommended in production workflows.
Beyond the basics, experienced email developers follow several additional guidelines to maximize compatibility:
border="0" and cellpadding="0" and cellspacing="0" on all tables to prevent default browser spacing.role="presentation" on layout tables so screen readers skip them.mso-line-height-rule: exactly; for precise line height control in Outlook.<!--[if mso]>) to serve Outlook-specific markup.This tool includes a library of pre-built email-safe HTML snippets that follow best practices out of the box. The snippets range from a minimal single-column table layout to a full email template with header, body, CTA button, and footer. Each snippet uses proper table structure, inline styles, and sensible defaults for widths and spacing.
Use snippets as starting points and customize them with your brand colors, fonts, and content. The "Full Template" snippet is particularly useful as a complete boilerplate that handles the outer wrapper, background color, content container, and footer links in one go.